Preconditioning cylinder



FIG. 1 is a left, front and top perspective view of a preconditioning cylinder showing our new design;

FIG. 2 is a right side elevational view thereof, on an enlarged scale;

FIG. 3 is a left side elevational view thereof;

FIG. 4 is a rear elevational view thereof;

FIG. 5 is a front elevational view thereof;

FIG. 6 is a top plan view thereof; and,

FIG. 7 is a bottom plan view thereof. 

The ornamental design for a preconditioning cylinder, as shown and described. 